This evidence review was compiled by members of the CITF Secretariat with the input from experts affiliated with the CITF and does not necessarily reflect the views of all CITF members.

by Mariana Bego

The World Health Organization (WHO) has recently introduced a new Variant of Interest (VOI) titled Mu or B.1.621. This new variant is becoming increasingly prevalent in parts of South America, namely Colombia and Ecuador. South African scientists are also closely monitoring the development of another new variant in the region called C.1.2, which has not yet been classified as a VOI. Both new variants have shown some signs of possible resistance to vaccines.

Key points:

  • The WHO recently named Variant Mu a VOI in their¬†epidemiological update.1 This variant was first identified in Colombia in January 2021 and has since then shown sporadic sightings in South America, the US, and Europe. Mu is now responsible for around 39% of infections in Colombia and 13% of infections in Ecuador. While Mu has several mutations that suggest a potential for some vaccine-escape, further research is needed to confirm this.
  • Variant C.1.2 was first described in a study2, published as a pre-print, from South Africa‚Äôs National Institute for Communicable The variant first identified in May 2021 carries several mutations previously linked to enhanced transmissibility and vaccine evasion. C.1.2 has since been found in the Democratic Republic of the Congo, Mauritius, New Zealand, Portugal, and Switzerland.

1- WHO Weekly epidemiological update on COVID-19. Edition 55, 31 August 2021.—31-august-2021

2- Scheepers C, Everatt J, Amoako DG, Mnguni A, Ismail A, Mahlangu B, Wibmer CK, Wilkinson E, Tegally H, San JE, Giandhari J, Ntuli N, Pillay S, Mohale T, Naidoo Y, Khumalo ZT, Makatini Z, NGS-SA, Sigal A, Williamson C, Treurnicht F, Mlisana K, Venter M, Hsiao N, Wolter N, Msomi N, Lessells R, Maponga T, Preiser W, Moore PL, von Gottberg A, de Oliveira T, Bhiman JN. The continuous evolution of SARS-CoV-2 in South Africa: a new lineage with rapid accumulation of mutations of concern and global detection. medRxiv 2021.08.20.21262342; doi: 10.1101/2021.08.20.21262342